Field of the Invention
The present invention relates to the optimization of a home-automation system comprising a plurality of communicating appliances able to exchange information among themselves via a local low-bitrate PLC network.
Description of Related Art
Several communication systems are used today for home-automation networks. One of the most popular, because it relies on the already existing electrical network, is Power Line Communication, or PLC.
Certain PLC solutions, offering a high bitrate, exhibit the major drawback of affording only short ranges, of the order of a few tens of meters. Others offer much more significant ranges, up to 500 meters, and are less expensive, but at the price of relatively low bitrates of the order of a few kilobits per second). These latter solutions are very well suited to numerous home-automation applications such as the management and the remote control of electrical appliances (lighting, heating, air-conditioning, roller blinds, ovens), sensors (of presence, of temperature, of humidity), of remote reading of intelligent meters (water, gas, electricity), etc.
However, such solutions will exhibit operating problems if the network gets denser, and exceeds a few tens of appliances communicating regularly over the network, because the available bandwidth will then no longer be sufficient co allow each appliance to communicate with its interlocutors or its relays.
Furthermore, even in the case where a home-automation system is envisaged with a limited number of appliances communicating via the local low-bitrate PLC network, the various phases of the electrical distribution network as well as the electrical energy meters installed at the premises of individuals generally allow the PLC signals to pass. It follows from this that other PLC devices outside the home-automation system considered may disturb the electrical line and reduce the bitrate. Likewise, the PLC communications between the communicating appliances of the home-automation system may go beyond the local network, and this may raise confidentiality problems.
By way of nonlimiting example, represented in FIG. 1 is a portion of a system for measurement and modulation in real time of a plurality of electrical devices using appliances communicating locally with one another over a PLC low-bitrate network. The principle of this system is described in particular in document WO 2008/017754 in the name of the Applicant. In the example illustrated, the portion of the system allows the management of a plurality of electrical devices (not represented), all powered from one and the same electrical line 1 of the electrical distribution network, situated for example in the residence of an individual, downstream of an electrical board 2. In this example, the system comprises four drive boxes 31 to 34 and five modulator boxes 41 to 45 organized according to a local PLC low-bitrate network. Each modulator box is able to be linked to one or more electrical devices (such as water heaters, electric radiators, air-conditioners, etc.), and is used to measure in real time the voltages and the currents consumed by these electrical devices, and to dispatch periodically, for example every ten minutes, the measurements to an external central platform 5 hosted by an Internet server. Accordingly, the measurements carried out by each modulator box are firstly transmitted to the drive box to which it is connected on the local PLC network, and then to the external platform 5 by way of a wireless communication modem (not represented) integrated into the drive box, and allowing a connection 6 of packet telephony type (GPRS, 3G or 4G) and/or of ADSL type. So as not to needlessly overload the figure, only the connection 6 between the drive box 32 and the platform 5 has been represented by a dashed line, to differentiate it from the PLC local network shown by a solid line. In the example represented, the drive box 31 thus serves as relay for the two modulator boxes 41 and 42, the drive box 32 serves as relay for the two modulator boxes 43 and 44, and the drive box 33 serves as relay for the modulator box 45. The measurements received by the external platform 5 are stored and can be viewed at any time and from anywhere by the user who can connect to his user space on the Internet by any known means. The external platform 5 is for its part able to dispatch to the drive boxes, through the wireless connection, commands to order the interruption of the power supply of all or some of the electrical devices linked to the various modulator boxes for a predetermined duration. The interruption periods are generally less than half an hour, so that the users affected by the cutting off of all or some of their electrical appliances, such as heaters or air-conditioners, do not experience any inconvenience. The monitoring of the power supply is performed by way of the modulator boxes.
This system, in addition to the possibility of tracking the consumptions by each user, makes it possible to manage simultaneously at the centralized platform a large quantity of modulator boxes and drive boxes and to modulate more easily, on a town, state, regional or national scale, the electrical power consumed by a collection of users, in particular during spikes in consumption, without it being necessary for the electrical energy suppliers to produce more electricity.
Today, the various drive and modulator boxes of such a system are all configured to transmit on the PLC network at one and the same predefined nominal transmission power. The PLC communication zone is represented schematically by the circle 7 in FIG. 1. Thus, the bandwidth on the electrical line 1 is already occupied, in the example of FIG. 1 by all the appliances of the PLC network, i.e. here by nine appliances, counting the four drive boxes 31 to 34 and the five modulator boxes 41 to 45. The addition of a further device on this PLC network or any disturbance originating from a device of a neighboring PLC network thus risks saturating the bandwidth. The bandwidth used may thus rapidly become critical on the electrical line, with the risk of blocking the network, certain appliances no longer succeeding in communicating.